1. Field of the Invention
The present invention generally relates to an optical disc recording and reproducing apparatus and, more particularly, to an optical disc recording and reproducing apparatus which records information on a rewritable optical disc such as a CD-RW.
2. Description of the Related Art
A minimum unit for reproduction of information recorded on a recording area of a compact disc (CD), a recordable optical disc (CD-R) or a rewritable optical disc (CD-RW) is defined as a block of a recording area. Each block can contain information of about 2,048 to 2,352 bytes.
A minimum unit for recording information on an optical disc such as a CD-R or a CD-RW is defined as a packet. Each packet comprises at least one user data block, five link blocks preceding the user data block and two link blocks subsequent to the user data block. The five link blocks preceding the user data block include one link block and four run-in blocks. The two link blocks subsequent to the user data block include two run-out blocks.
The link blocks are required for interconnecting a plurality of packets when information is recorded on an optical disc such as a CD. The link block does not contain user data. It should be noted that a rule for recording data on a CD is defined by a predetermined standard. Such a rule is referred to as a "linking rule".
There are two methods for recording data on an optical disc such as a recordable compact disc (CD-R) or a rewritable compact disc (CD-RW). One of the methods is referred to as a "track at-once method" and the other is referred to as a "packet write method".
The track at-once method is for recording information on a track all at one time by using a single packet. The user data blocks in the track are consecutive, and there are no link blocks between the user data blocks. A single track constitutes a recording unit, and ninety-nine tracks can be formed on the optical disc at maximum. A start address and an end address of each track are recorded on a separate area of the optical disc as a "table of contents (TOC)".
On the other hand, the packet write method is for recording information on a track by dividing the track into a plurality of packets so that the information is recorded on an individual packet basis. Since this method records information by each individual packet, each user data block is discretely located in a single track and link blocks are provided between adjacent ones of user data blocks.
The packet write method is classified into two types, that is, a "fixed packet write method" and a "variable packet write method". In the fixed packet write method, a number of user data blocks within a track is set to a fixed number. The number of user data blocks within a packet is referred to as a packet length or packet size. On the other hand, in the variable packet write method, packets having various packet lengths are provided in a single track.
The Universal Disc format (UDF) is a file system that uses the fixed packet write system. The UDF is used by various devices. The UDF utilizes a recording format that takes advantage of a feature of each device.
In a conventional CD-R drive such as one disclosed in Japanese Laid-Open Patent Application No.7-141660, when the recording is performed in accordance with the packet write method, data to be recorded is added to previously recorded packets since only an addition of data is allowed for the CD-R. Accordingly, the UDF uses a variable packet write method referred to as a sequential UDF which can perform a recording only by adding data after the previously recorded data. Thus, there is no need to consider a format.
On the other hand, a CD-RW drive is capable of recording data on a CD-RW by overwriting. Thus, the CD-RW drive uses a random UDF which records data by each packet unit and reproduces the data by each block.
In order to record and reproduce data at random, the random UDF requires a formatting operation by previously recording packets on the entire recording area or a designated area of the CD-RW, each of the packets having a fixed length, so that the entire recording area or the designated area are filled by the packets. By this formatting operation, data can be randomly recorded on the recording area of the CD-RW, or data recorded on the CD-RW can be randomly reproduced.
However, when the above-mentioned formatting operation is performed, it takes a long time to fill the entire recording area or the designated area of the CD-RW by the packets. Thus, there is a problem in that a recording or reproducing operation cannot be performed and completion of the formatting operation data must be waited for when the formatting operation is being performed.
The recording capacity of the CD-RW is represented by a time for continuously performing a recording operation. For example, one minute of recording corresponds to 9 megabytes, and data corresponding to about 74 minutes can be recorded on a CD-RW. Thus, it takes about 40 minutes to complete a recording of data including the TOC even if the recording is performed at a double recording speed. This means that one must wait for about 40 minutes until a formatting operation is completed in order to initially use a blank or new CD-RW.